Nowadays computers are widely used in almost every aspect of people's life. Desk top computers, laptops, notebook computers or NetTVs are ubiquitous. In a low light or dark environment lack of light makes correct striking of the keyboard difficult that could result in inaccurate signal output. To solve this problem many types of luminous keyboards have been proposed in prior art, such as U.S. Pat. Nos. 6,284,988, 6,322,229, 6,199,996, 6,554,442 and 6,179,432, and R.O.C. patent publication Nos. 509955, 465777, 535385, 438035, 570235, 468833 and 516671. They mostly have a built-in luminous sheet to emit light to enable users to clearly determine the striking position on the keyboard.
For instance, R.O.C. patent publication No. 509955 discloses a luminous keyboard which has a keyboard portion and a backlight means beneath the keyboard. The backlight means provides a light source below the keyboard portion for the keyboard portion. In an embodiment the backlight means includes a light directing plate which has a reflective portion, a reflective plate and a light source. The light source is located at one side of the light directing plate. The light source emits light which is transmitted through the light directing plate below each key. Then the reflective portion reflects the light to illuminate the key.
R.O.C. patent No. I269333 provides a keyboard with a backlight structure. It has a light transmission space located between a base board and a bridge board. The bridge board has at least one light directing portion corresponding to the interval of the keyboard portion and light transmission space. Light emitted by a light source projects to each key through the light transmission space and light directing portion.
However, in the two patents previously discussed light is transmitted to the keyboard through a light directing layer, a light directing object or other light directing aids. By adding the light directing layer or light directing object the thickness and weight of the keyboard increase. Moreover, such a design makes fabrication and assembly more complex. It is against the prevailing trend of computer equipment that demands thin and light.